1. Field of the Invention
The present invention relates to a servomotor control apparatus, and in particular relates to a servomotor control apparatus that controls a machine having one or a plurality of movable portions each driven by a servomotor and that prevents the position of the machine from differing due to a brake malfunction.
2. Description of Related Art
In servomotor control apparatuses, a method for maintaining the posture of an arm by powering a motor, when an operation command is issued to the motor in a state in which a brake is operated and a reduction in braking performance is detected by a comparison between an operation amount of the motor and a predetermined threshold value, is proposed (for example, Japanese Unexamined Patent Publication (Kokai) No. 2005-254410).
However, according to this conventional art, the posture of the arm is maintained by powering the motor, only when the detection of the braking performance is performed and the reduction in the braking performance is detected. Thus, in the event that the brake is fully released due to a sudden brake failure or the like, the conventional art has no means to prevent the position of the machine from differing.